Mythbusters did a segment where they put different ammo into a barrel and set them on fire. No projectiles, they just ignited like firecrackers....
The bullets and casings might act like shrapnel in that case, but I think it’s the gun barrel that directs all that kinetic energy onto a single target and makes it effective.
“No projectiles, they just ignited like firecrackers....”
Yes, we used to throw them in the campfire once in awhile when we were kids. Like firecrackers. But if they heat slowly they are more of a just a fizzle because the lead melts and flows out before the propellant lights and fizzles. Lead melts at 327 degrees.